Some working machines, for example, construction machines such as large hydraulic excavators operating at sites such as mines are required to continuously operate 24 hours 365 days with virtually no stop. Such machines need to be preventively maintained in their best condition by conducting maintenance operations before the machine comes to an abnormal stop. In general, special maintenance personnel periodically checks and examines the machines for abnormalities, and if an abnormality is found, a necessary maintenance operation is performed to maintain the machine in a good condition.
To perform such checking and maintenance operation, however, the machine needs to be stopped. For an operator or manager who wishes to operate the machines continuously, the checking and maintenance operations can be an operational obstacle so long as the machines are in good condition.
In view of this, abnormality-diagnosing techniques have been developed that use various sensors to analyze the machine condition and monitor for abnormalities. Importance of preventive maintenance by use of an abnormality-diagnosis technique has become recognized in view of preventing occurrence of machine trouble by detecting abnormalities and taking early maintenance measures before the machine comes to an abnormal stop.
Meanwhile, although machine manufacturers are deeply committed to developing diagnostic algorithm for abnormality diagnosis, difficulty with the development of the algorithm has prevented appropriate diagnosis to be made in some cases. The reason appropriate determination is difficult is that the experimental environment in which experiments were performed in the algorithm development differs from the operational environment and operational form in which a user uses the machines.
Under such situations, inventions have been devised that are intended to conduct determination according to measurement results obtained in an actual environment. Patent Documents 1 and 2 describe inventions that detect abnormality in machines or plant equipment using statistical properties or similarity levels of input signals indicating the operational condition of the machine or plant equipment. Patent Document 3 discloses an invention that processes data through interactive dialog with a user so as to render cluster classification appropriate. Patent Document 4 describes an invention that eliminates determination errors by detecting sensor abnormalities as well.